Could I Be Pregnant If My Period Is Delayed Despite A Negative Urine Test And Premenstrual Symptoms?

Hello Doctor, I saw my menstruation on march 21st through to 26th. And now I m suppose to have see it again this month, but I haven t I did the first urine test on 16th april and it was negative. Could I be pregnant? Thou I have premenstrual feelings. What could have cause the delay.